<html>
    
    <script src="jquery-3.3.1.js"></script>
    <script>
        var div1 = $("#ball");
        console.log(this);
    </script>
    <body>
    <div>
        <ul id="ball">
        <li>足球</li>
        <li>网球</li>
        <li class="basketball">篮球</li>
    </ul>
       </div>
    </body>
</html>